Process of treating drawn metal.



A. PACZ.

PROCESS OF TREATING DRAWN METAL. APPLICATION FILED APR. :3. m4. nnazwao nvls. ma.

Patented Oct. 8,1918."

' INSZLE'NTDR. ALADAR Razz, fi His AZ'TURWX' WZTNE's'sEs TD STATES PATENT OFFICE.

ALADAB' PACZ, OF CLEVELAND, OHIO, ASSIGNOB TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK. I

PROCESS OF TREATING DRAWN METAL.

Specification of Letters Patent.

Patented Oct. 8, 1918.

Application filed April 13, 1914, SerialNo. 831,612. Renewed May 18, 1918. Serial No. 235,391.

To all whom it may concern.

Be it known that I, ALADAR PAoz, a c1t1- zen of the United States, residing at Cleveland, county of Guyahoga, State of OlllO, have invented certain new and useful Improvements in Processes of Treating Drawn Metal, of which the following is a speclfication.

My invention relates to the manufacture of metal wire such as that used for making filaments and filament supports for incandescent lamps. More specifically, my invention comprises a process of treating during the drawlng process, or immediately thereafter, wire such as that used for filaments and so as to render it better adapted for the work which it is called upon to perform.

My invention is particularly applicable to tungsten wire which is used for filaments or filament supports in electric incandescent lamps. Drawn tungsten wire is produced according to the process described in Coolidge Patent No.*1,082,933, issued Dec. 30, 1913, and my invention is particularly adapted to the treatment of wire which hasbeen produced accordin to this process. As disclosed in the said oolidge patent, the process of drawing down the wire comprises a number of steps, the wire being reheated a number of times preparatory to passing through the various dies. My invention may be applied from time to time during the drawing down of the metal according to the said process, but I prefer to apply it after the Wire has been drawn down to approximately the final size for use as a filament or.

su port in an incandescent lamp.

ungsten wire produced prior to my invention, while very eflicient and giving. good results in lamps, was rather difiicult to mount upon the supports without a preliminary' shaping, which required theheating of each filament. In order to keep the wire straight, the practice was to crimp it. Moreover, on account of the necessity of using a carbonaceous lubricant in drawing down wire a certain amount of carbon was'physically or chemically included in the filament which naturally was of more or less disad-' vantage in the lamps.

I have found that by giving the wire-a preliminary heating at approximately. red heat in the presence of an oxidizing agent, preferably air or oxygen, the metal becomes inelastic and capable of taking a permanent I do not wish to be confined to any par-- ticular theory as to, what takes place during the process constituting my invention. It is probable that the action which takes place is a combined chemical and physical one and includes the removal of impurities, such as carbon, and a change in the sizes of grains due to rearrangement of molecules or ulti-. mate particles of the metal. The wire which has been treated according to my invention is much superior to that heretofore produced in point of pliability and flexibility. It is also much softer and takes a permanent set much more easily, remaining straight without requiring to be crimped.

In the drawing I have illustrated an a paratus by means of which one species 0 my invention may be carried out. Figure 1 thereof is a sectional elevation of such an apparatus and Fig. 2 is a transverse section thereof on the line 22.

In applying the apparatus illustrated in the drawing to the practice of my invention, the wire, which may be ductile tungsten roduced by the process described in the C bolidge patent hereinbefore referred to, is placed upon the reel 10 and is led through the apparatus to the reel 11 upon which it is wound by a suitable rotating mechanism 12. The tube 13, which is suitably supported by standards 14 is preferably cylindrical in shape and has a slot 15 formed in the,top thereof. At each end the said tube is provided with a mercury container 16 through which the wire passes and makes contact. A source of electric energy is connected by means of the leads 17 to the mercury contacts.

The tube 13 is open to the air on account of the slot in the top thereof and the air .probably serves as an oxidizing medium to combine with the carbon and possibly other heated approximately to dull redness so that the members 21.

' To the left of Fig. 1 is illustrated a second tube 18. This tube is closed at each end by the plugs 19, each of which supports a mereury contact 20 through which the wire passes. This tube is sultably supported-by The tube 18 is filled with a gas from which oxygen and other reagents which would attack the metal are absent. I prefer a reducing atmosphere and have used successfully forming gas composed of approximately 88 parts nitrogen .and 12 parts hydrogen. This reduces any tungsten oxid formed during the previous treatment. The voltage between the contacts 20 is so regulated that the wire will be heated at least 'to a white heat.

In order that the wire may be observed during its passage through tube 18, this tube is preferably composed of glass or other transparent material, the length of the tube .18 must be such that the Wire will not "be subjected toolong to the high. heating.

I have found that, when the'first treatment is performed under the conditions heretofore stated, the distance between the contacts in tube 18 should be approximatelyv seven inches.

According to one theory which I have evolved, in addition to having the physical efl'ect hereinbefore referred to, the heating of the wire in the oxidizing atmosphere causes the carbon near the surface to burn.

and that which is contained within the wire to be sweated out to the surface. This at sweating process may include the formation 5' of a tungsten oxygen carbon compound.

During the subsequent high heating of wire in the absence of oxygen, any compounds which mayhave been formed by the oxygen are broken up and driven ofi.

During the-. second treatment the wlre is shrunk and; cleaned. The action which probably takes place is that the spaces formerly occupied by the carbon and-other impurities are filled up with the pure-metal, while any oxid' which may have formed is removed by the hydrogen.

wire at various stages of the drawing process. This has. the advantage over treating the wire of the final size that the carbon or other impurity. is not allowed-to penetrate so far into the wire and its removal is'there fore acomplished more easily.

The bent results have been achieved in temperature whi 1 dizing agent and afterward heating it to a connection with tungsten wire produced from material whichhas been treated .SQ as to obviate subsequent ofi'-settingwhen used as a filament, for example, as describedin the Coolidge patent hereinbefore referred to and in Frech Patent No. 1,089,757, March 10, 1914. However, good resultshave been secured with other wire.

' I What I claim as new and desire to secure by Letters Patent of the United States, is,-.

1. The process of treating drawn metal which has been subjected to the action of impurities during its manufacture which consists in heating it at a comparatively lowtemperature while in contact with a reagent which will combine with said impurities and afterward heating it to a comparatively high temperature in the absence of said reagent.

2. The process of treating drawn tungsten which has been subjected to the action of impurities during its manufacture which consists in heating it at a comparatively low e in contact with an oxicomparatively high temperature in theabsence of said oxidizing agent. 7

3. The process of treating drawn tungsten which has been sub ected to the action of carbonaceous material during its .manufacture which consists in heating it to a comparatively low temperature in the presence of a reagent which will combine with carbon or carbon compounds and afterward heating it to a high temperature in the absence of such re-agent.

. 4. The process of treating drawn tungsten which has been subjected to the action of carbonaceous material during its'manufacture which consists in heating it to a comof an oxidizing agent and afterward heating it to a high temperature in the absence of such oxidizing agent.

5. The process of treating drawn tungsten which has been subjected to the action of paratively low temperature in the pressence 7 carbonaceous material during its manufacture which consists inheating it to a comparativelylow temperature in-the pres 'enceof air and afterward heating it to a high temperature in an inert or reducing atmosphere.

bonaceous material duringits manufacture" 6. The pro ess of treating drawn tungsten which consists in heating it to a low red heat in the presence of an oxidizingagent My process may be performed upon the which has been subjected to the-action of carbonaceous material during its'manufacture whlch consists in heating itto a low red heat in the presence of an' oxidizing'agent and afterward heating it approximately to a White heat in the presence of a reducing agent.

8. The process of treating drawn tungsten 5 wire which consists in holding it at substantially red heat for a short period and afterward holding it at a White heat.

In witness whereof, I have hereunto set my hand this 26th day of March, 1914. 

